Here are the steps needed to convert from CentOS 8 to CentOS 8 Stream.
First backup anything important, the conversion process is fairly simple and smooth with no issues usually but just in case make backups of important stuff if anything goes wrong.
Second step is to install all pending updates on current CentOS 8 installation.
Update to latest version of packages with following command:
dnf update
After updates are installed reboot the machine to make sure latest kernel version is loaded and that everything is working normally with latest package versions before migrating to CentOS 8 Stream:
reboot
After the machine is back up install centos-release-stream package with following command
dnf install centos-release-stream
After centos-release-stream has been installed swap repos from CentOS Linux 8 repos to CentOS Stream 8 repos with following command
dnf swap centos-linux-repos centos-stream-repo
After repos have been swapped check if correct repos are listed in dnf with following command
dnf repolist
You should see CentOS Stream 8 repos listed now instead of CentOS Linux 8 repos that were there before.
When CentOS 8 Stream repos have been set sync all installed packages with CentOS Stream versions using following command:
dnf distro-sync
After packages have been synced you can use cat /etc/redhat-release or hostnamectl command to check and confirm that you are now running CentOS Stream 8 OS.
This is an output of hostnamectl command before the sync:
hostnamectl
Static hostname: server0
Icon name: computer-vm
Chassis: vm
Machine ID: ba45dac81f4e4f6f9c9bb2657914c81e
Boot ID: e36de8bd66f1467983104acd47defac0
Virtualization: kvm
Operating System: CentOS Linux 8
CPE OS Name: cpe:/o:centos:centos:8
Kernel: Linux 4.18.0-348.2.1.el8_5.x86_64
Architecture: x86-64
This is an output of hostnamectl command after dnf sync command has been run:
hostnamectl
Static hostname: server0
Icon name: computer-vm
Chassis: vm
Machine ID: ba45dac81f4e4f6f9c9bb2657914c81e
Boot ID: 526a47bb15b4420db4cc3cf364af9555
Virtualization: kvm
Operating System: CentOS Stream 8
CPE OS Name: cpe:/o:centos:centos:8
Kernel: Linux 4.18.0-348.7.1.el8_5.x86_64
Architecture: x86-64
Reboot the server and check for any possible issues.